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vfio/platform: keep logical vm_pgoff in MMIO region mmap

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vfio_platform_mmap_mmio() overwrites vma->vm_pgoff with the physical
frame number of the MMIO region and passes it to remap_pfn_range().
The VMA is inserted into the device file's mapping->i_mmap interval
tree keyed by vm_pgoff, which VFIO expects to be the logical file
offset: the core links every device mmap to the device inode's
i_mapping precisely so that unmap_mapping_range() can revoke all
mappings associated with a device (see vfio_device_cdev_open()).

With a raw PFN in vm_pgoff the interval tree entry lands in the wrong
coordinate space and unmap_mapping_range() cannot find the VMA,
leaving stale MMIO mappings behind any revocation attempt.  Keep
vm_pgoff in the logical VFIO offset space, as vfio-pci does, and pass
the physical PFN to remap_pfn_range() explicitly.

This is defensive hygiene: none of vfio-platform, vfio/fsl-mc and
vfio/cdx call unmap_mapping_range() today, so no reachable
stale-mapping issue exists.  Keeping vm_pgoff logical preserves the
VFIO core contract for any future revocation path.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Abdifatah Suruur <suruurism@gmail.com>
Link: https://lore.kernel.org/r/20260929094848.7439-5-suruurism@gmail.com
Signed-off-by: Alex Williamson <alex@shazbot.org>
This commit is contained in:
Abdifatah Suruur 2026-09-29 12:48:45 +03:00 committed by Alex Williamson
parent 9c5cd385d2
commit a9ce237e1a
1 changed files with 2 additions and 3 deletions
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5
drivers/vfio/platform/vfio_platform_common.c
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@ -559,9 +559,8 @@ static int vfio_platform_mmap_mmio(struct vfio_platform_region region,
return -EINVAL;
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
vma->vm_pgoff = (region.addr >> PAGE_SHIFT) + pgoff;
return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
return remap_pfn_range(vma, vma->vm_start,
(region.addr >> PAGE_SHIFT) + pgoff,
req_len, vma->vm_page_prot);
}